Add sd_event loop and callback handler

Change-Id: I032d1156be2b8082fdf347a60ec883a9bc0038ae
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>
diff --git a/configure.ac b/configure.ac
index 40100c7..709ed05 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,6 +19,7 @@
 LT_INIT
 
 # Checks for modules
+PKG_CHECK_MODULES([SYSTEMD], [libsystemd >= 221], ,[AC_MSG_ERROR([Could not find systemd...systemd developement package required])])
 PKG_CHECK_MODULES([PHOSPHOR_LOGGING], [phosphor-logging],, [AC_MSG_ERROR([Could not find phosphor-logging...openbmc/phosphor-logging package required])])
 
 # Create configured output